Automatic fiber optic connectorization and inspection system (AFOCIS)

ABSTRACT

A method and apparatus are provided for inspecting an end face of an optical fiber. The apparatus includes a memory device for storing images of acceptable end faces and unacceptable end faces, and an imaging system for obtaining an image of the end face of the optical fiber. Further, the apparatus includes a means, responsive to said imaging system, for comparing the image of the end fare of the optical fiber with the images of acceptable end faces and unacceptable end faces to automatically determine if the optical fiber is acceptable.

This application claims the benefit of provisional application60/025,778 filed Sep. 30, 1996.

FIELD OF THE INVENTION

The present invention relates generally to a method and apparatus forconnectorizing, testing and inspecting fiber optic cables and, morespecifically, a method and apparatus for automatically connectorizing,testing and inspecting fiber optic cables.

BACKGROUND OF THE INVENTION

Fiber optic networks are employed in an increasing and varied number ofapplications for transmitting voice, data and other information. Forexample, fiber optic networks are utilized in a wide variety ofaerospace applications for transmitting data at high speeds and withrelatively low loss. Each of these fiber optic networks includes anumber of optical fiber links. In turn, each optical fiber linkgenerally includes a fiber optic connector mounted to the opposed endsthereof. This connectorization process is further complicated since eachend face of the optical fiber must generally be precisely polished andcleaned after mounting the ferrule, but before mounting the remainder ofthe connector thereon. Thus, there is a risk of losing this expensiveferrule, if the polishing process is not successful. The industry'sfailure rate of polishing is approximately 10%, and the cost of eachferrule, such as ITT Cannon part number NFOC-F15PB, is $150. Inaddition, the connectorized optical fiber must oftentimes be inspectedto insure compliance with performance specifications thereby furtherincrease on labor costs. As a result, it typically takes approximately20 minutes to manually connectorize one end of a fiber optic cable.

Current techniques for mounting connectors upon the end portions offiber optic cables are generally quite complicated and labor intensiveand may oftentimes require specially trained technicians and inspectors.As a result, the connectorization costs may quickly become unnecessarilylarge, particularly in view of the large number of fiber optic cablesthat must typically be connectorized by an aircraft manufacturer. Inaddition, current connectorization techniques often have poorrepeatability, thereby producing fiber optic cables which have a widevariety of operating characteristics.

A number of automated techniques have therefore been developed forautomatically mounting connectors upon the end portions of a fiber opticcable. For example, U.S. Pat. No. 5,394,606 to Isamu Knoshita, et al.and U.S. Pat. No. 4,944,079 to Kunio Nakamura, et, al. describeautomated devices for connectorizing a fiber optic cable. Unfortunately,each of these automated techniques is limited to mounting one particulartype of connector upon the end portion of a common fiber optic cable andis not designed to mount the wide variety of connectors upon the endportions of respective different fiber optic cables that are demanded bymany modern applications, such as aerospace and local area network (LAN)applications.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide animproved method and apparatus for automatically connectorizing fiberoptic cables.

It is another object of the present invention to provide a method andapparatus for automatically mounting any one of a variety of connectorsupon the end portion of a fiber optic cable.

It is a further object of the present invention to provide an improvedmethod and apparatus for automatically inspecting and classifyingoptical fibers during the connectorization process.

It is yet another object of the present invention to provide an improvedmethod and apparatus for automatically testing the optical performanceof a fiber optic cable after the connectorization process.

These and other objects are provided, according to one embodiment of thepresent invention, by a method and apparatus for mounting any one of aplurality of types of connectors upon the end portion of a fiber opticcable. According to this embodiment, the automated fiber opticconnectorization apparatus includes a memory device for storing datarelating to a plurality of types of connectors, such as the parts andsupplies required to assemble each type of connector, and data relatingto the fiber end-face geometry and corresponding optical performancedata. The automated fiber optic connectorization apparatus also includesa controller for receiving input data that describe the detailedrequirements for each fiber optic link, such as from a system operator,a wire data list, or other source, that specifies the type of connectorto be mounted upon the end portion of the optical fiber. Based upon thisinput, the controller determines the components, i.e., the parts andsupplies, required to mount the specified type of connector upon the endportion of the fiber optic cable based upon the data stored by thememory device. The automated fiber optic connectorization apparatus alsoincludes means for obtaining the necessary components and means forassembling these components upon the end portion of the fiber opticcable. As a result, the automated fiber optic connectorization apparatusof this embodiment of the present invention can automatically mount thespecified type of connector of the type upon the end portion of thefiber optic cable.

In addition to inputting the type of connector, the system operator,wire data list, or other source can also specify the length of theresulting fiber optic cable. Accordingly, the automated fiber opticconnectorization apparatus of one embodiment includes a cutter forautomatically cutting and stripping the cable components to varyinglengths. Notably, the automated fiber optic connectorization apparatuscan also include means for automatically polishing the end face of theoptical fiber and inspecting the end face prior to mounting theconnector upon the end portion of the optical fiber. Thus, the task ofmounting the connector proceeds only if the polished surface of thefiber end-face has been inspected and is Pound to be acceptable.

To handle this task, a cassette is also provided for preparing the endface of an optical fiber, such as for polishing or cleaning the end faceof an optical fiber. The cassette Includes a housing defining a windowand a supply reel and a take up reel disposed within the housing. Thecassette contains preparatory tapes, such as a polishing strip and acleaning strip, that advances from the supply reel to the take up reelfor preparing the end face of the optical fiber. Further, the cassetteincludes means for directing the tape by the window defined by thehousing such that the tape contacts and prepares the end face of theoptical fiber, such as by polishing or cleaning the end face of theoptical fiber. For example, the directing means can include a resilientpad aligned with the window defined by the housing and disposed interiorof the preparatory tape within the housing for supporting thepreparatory tape during contact with the end face of the optical fiber.In order to properly prepare the end face of the optical fiber, thecassette also preferably includes means for controllably moving thehousing relative to the end face of the optical fiber.

The automated fiber optic connectorization apparatus can also includemeans for automatically inspecting the optical fiber after the end faceof the optical fiber has been polished. According to this embodiment, anautomated optical fiber inspection apparatus is provided forautomatically inspecting and classifying the polished end face of anoptical fiber before proceeding to the next step, i.e. prior toconnectorizing the fiber optic cable. According to this embodiment, theautomated optical fiber inspection apparatus includes a memory devicefor storing predefined data sets relating to at least one characteristicof the end face of the optical fiber. For example, the data sets can berepresentative of images of acceptable end faces and unacceptable endfaces.

The automated optical fiber inspection apparatus of this embodiment canalso include an imaging system for obtaining an image, preferably acomposite image generated from a series of captured images,characterizing the end-face contour of the optical fiber and means forcomparing this composite image of the end face of the optical fiberagainst the predefined data sets relating to at least one characteristicof the end face of the optical fiber so as to automatically determinethe “best-match” data set. Since each predefined data set has beenclassified as acceptable or unacceptable, the automated optical fiberinspection apparatus determines the acceptability of the end-facecontour based upon the classification of the best-match data set.According to one advantageous embodiment, the automated optical fiberinspection apparatus can also include means for automaticallydetermining if an unacceptable optical fiber can be corrected, such asby repolishing, or if the unacceptable optical fiber must be completedreworked, beginning by recleaving the end portion of the optical fiber.The automated optical fiber inspection apparatus can also include means,such as a test station, for testing the connectorized fiber optic cableto guarantee predefined optical operating parameters, such as opticalloss or optical back-reflection.

During the process for automatically inspecting and connectorizing afiber optic cable, the fiber optic cable is preferably carried by anoptical fiber cartridge assembly which presents the appropriate segmentof the fiber optic cable for jacket stripping, fiber cleaving, andend-face polishing operations. According to this embodiment, the opticalfiber cartridge assembly includes an optical fiber cartridge including aplatform, a reel rotatably mounted upon the platform, and first andsecond gripping means mounted upon the platform for holding the firstand second opposed ends of the optical fiber, respectively. The opticalfiber cartridge of this embodiment also includes means for rotating theplatform relative to the reel such that the optical fiber is wound aboutthe reel. In this regard, the optical fiber cartridge can include meansfor raising he reel relative to the platform during the rotation of theplatform relative to the reel.

By providing for the automatic connectorization of fiber optic cables,the automatic fiber optic connectorization method and apparatus of thepresent invention significantly reduces the time and labor required tomount connectors upon the end portions of fiber optic cables, therebyincreasing productivity. As a result, the automated fiber opticconnectorization apparatus can be readily operated by technicians withvery little training. The efficiency and yield of the automaticconnectorization process of the present invention is further advanced bythe automated optical fiber inspection apparatus of one embodiment thatinsures that the optical fibers have been properly polished prior tomounting of the expensive connectors and, if an optical fiber isunacceptable, automatically determines if the optical fiber must berepolished or otherwise reworked. In contrast to conventional automatedconnectorization techniques, the automated fiber optic connectorizationapparatus of the present invention can advantageously mount any one of aplurality of types of connectors upon the end portion of a fiber opticcable based upon input by the system operator or other source, therebypermitting rapid customization of the automated fiber opticconnectorization apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an automatic fiber opticconnectorization apparatus of one embodiment of the present invention.

FIG. 2 is a block diagram of one advantageous embodiment of theautomatic fiber optic connectorization apparatus of the presentinvention.

FIGS. 3A and 3B are perspective views of the optical fiber cartridgeassembly of two advantageous embodiments of the present invention.

FIGS. 4A and 4B are end and plan views, respectively, of a gripperaccording to one embodiment of the present invention.

FIGS. 5A and 5B are plan views of an optical fiber cartridge accordingto one embodiment of the present invention that illustrates the windingof fiber optic cable upon the reel of the optical fiber cartridge.

FIG. 6A is an overall block diagram of the operations performed by theautomatic fiber optic connectorization apparatus of one embodiment ofthe present invention.

FIG. 6B is a block diagram of the operations performed to prepare afiber optic cable according to one embodiment of the present invention.

FIG. 6C is a block diagram of the operations performed to test andverify product conformity according to one embodiment of the presentinvention.

FIG. 6D is a block diagram of the operations performed to grind andpolish the end face of an optical fiber according to one embodiment ofthe present invention.

FIG. 6E is a block diagram of the operations performed to inspect theend face of an optical fiber according to one embodiment of the presentinvention.

FIG. 6F is a block diagram of the operations performed to mount aconnector upon the end portion of a fiber optic cable according to oneembodiment of the present invention.

FIG. 6G is a block diagram of the operations performed to inspect aconnectorized fiber optic cable according to one embodiment of thepresent invention.

FIG. 7 is a perspective view of an end portion of a fiber optic cable inwhich the various layers have been partially removed or stripped forpurposes of illustration.

FIGS. 8A and 8E are perspective and fragmentary perspective views of acassette for preparing the end face of an optical fiber according to oneembodiment of the present invention.

FIGS. 9A-9D depict four phase shift images (or interferrograms) withphase shifts of π/2, π, 3π/2 and 2π, respectively.

FIG. 9E is a composite phase shift image based upon the four phase shiftimages of FIGS. 9A-9D.

FIG. 10 is a representation of the phase shrift analysis and the processof generating first a composite phase image from the four phase shiftimages and then a normalized phase pattern from the maximum and minimumvalues of the composite phase image according to one embodiment of theautomated optical fiber inspection apparatus of the present invention.

FIGS. 11A and 11B are digitized composite images before and after edgeenhancement, respectively, which enhance the distinctive pattern of animage which otherwise may be obscured due to the blurring boundaries ofthe features.

FIGS. 12A-12D are a composite image and related contour maps of an endface of an optical fiber having a minor defect that is correctable byfurther polishing.

FIGS. 13A-13D are a compose image and related contour maps of an endface of an optical fiber having a serious defect that cannot becorrected by further polishing.

FIG. 14 is a schematic diagram of the automated optical fiber inspectionapparatus of one embodiment of the present invention.

FIG. 15 is a block diagram of the operations performed by oneadvantageous embodiment of the automatic optical fiber inspectionapparatus of the present invention.

FIGS. 16A-16C show the end faces of various optical fibers that may becorrected by further polishing.

FIGS. 17A-17F show the end faces of various optical fibers that cannotbe corrected by further polishing.

FIG. 18 is a block diagram of the operations performed to determine ifan end face of an optical fiber is acceptable according to oneembodiment of the present invention.

FIG. 19 is a schematic view of the optical performance testing apparatusaccording to one advantageous embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scone of the invention to those skilled in the art. Likenumbers refer to like elements throughout.

Referring now to FIG. 1, an automatic fiber optic connectorizationapparatus 20 is illustrated. Although the automatic fiber opticconnectorization apparatus is not unusually large, it is anticipatedthat the actual size of the automated fiber optic connectorizationapparatus will be further reduced with further advances inminiaturization techniques. As explained below, the automatic fiberoptic connectorization apparatus processes raw optical fiber based uponinput provided by the system operator or other source, such as acomputer network or another type of external computer, to produce afiber optic cable that is cut to length and that has been connectorizedwith the appropriate connectors and inspected. Moreover, the automaticfiber optic connectorization apparatus tests the optical fiber duringand following to connectorization process to insure compliance withperformance specifications.

As shown in block diagram form in FIG. 2, the automatic fiber opticconnectorization apparatus 20 preferably includes a central commuter 22that operates under software control to perform the various functionsshown in FIG. 2 and described hereinbelow. Although the automatic fiberoptic connectorization apparatus can include many different types ofcentral computers, the central computer of one advantageous embodimentis an Intel Pentium processor operating at 120 MHz or higher processingspeeds. The central computer includes or is otherwise associated with amemory device 24 for storing a variety of data. In particular, thememory device stores data input by the system operator or other sourceas well as data downloaded from a fiber optic cable and connectordatabase 26, i.e. a wire data list. As shown in FIG. 2, for example, thesystem operator enters data via a fiber optic cable configurationworkstation 28. In turn, the fiber optic cable configuration workstationaccesses the fiber optic cable and connector database and provides thecomputer with the appropriate data for constructing the cable specifiedby the system operator. Although he fiber optic cable and connectordatabase is depicted to be external to the central computer, the fiberoptic cable and connector database is preferably stored in memory withinthe central computer. In addition, although a fiber optic cableconfiguration workstation is provided for entry of data by the systemoperator, the necessary data can be downloaded or otherwise provided byanother computer system without departing from the spirit and scope ofthe present invention.

Although a wide variety of data can be provided by the system operatoror downloaded from a wire data list or other source, the data typicallyincludes the length of the fiber optic cable, the connector type foreach end of the fiber optic cable, the type of optical fiber and/orfiber optic cable, the finished fiber geometry requirements and theoptical performance requirements, such as optical loss and optical backreflection. The finished fiber geometry requirements generally dependupon the type of polish, i.e., physical contact or convex method, flatpolish or concave polish. With each type of polish, the data preferablyprovides the angular tolerance. However, the data also provides thedepth of a concave polish, the height of a flat polish and the radius ofcurvature and height (apex) of an optical fiber having a convex endface.

In the illustrated embodiment, the central computer 22 passes data andcontrol information to a programmable controller 30, such as an actuatorcontroller or a micro-positioner, which controls the various hardwarecomponents of the automatic fiber optic connectorization apparatus 20.Preferably, the controller has a flexible data input/output interfacethat can receive various data inputs, e.g., downloaded from a wire list,relating to a variety of fiber optic link characteristics includinglength, loss, back reflection, connector type, component parts, cabletype, fiber size and internal adaptive component, i.e., the type ofrobotic connector adapter for holding and moving the connector duringthe various operations. Although the controller is depicted to beseparate from the central computer, the central computer may include thecontroller without departing from the spirit and scope of the presentinvention. Once the central computer has received instructions from thesystem operator or other source, the central computer converts the rawdata to precise control commands for each connectorization step such asmarking cable cut length, end strip lengths, epoxy application, or fiberpolishing, as described below. The controller feeds the raw fiber opticcable into a cable cutting and marking unit 32, either directly or byfirst winding the fiber optic cable onto an optical fiber cartridge 34which is then moved Into an aligned position relative to the cablecutting and marking unit.

As shown in FIGS. 3A and 33, the optical fiber cartridge 34 includes aplatform 36 and a reel 38 rotatably mounted upon the platform. The hub42 of the reel must also be of sufficient diameter to prevent the fiberoptic cable from bending more sharply than the predetermined bend radiusof the fiber optic cable. For example, the hub of the reel of oneadvantageous embodiment has a diameter of at least 4 inches.

The optical fiber cartridge 34 also includes first and second grippingmeans mounted upon the platform 36 for holding the first and secondopposed ends of the optical fiber, respectively. As shown in FIGS. 4Aand 4B, each gripping means preferably includes a gripper 44 forreceiving and securely holding the fiber optic cable and, morepreferably, first, second and third grippers for holding the variousstripped sections of the fiber optic cable, such as the bare opticalfiber, the optical fiber surrounded by a buffer layer (inner jacket) andthe cable jacket (outer jacket), respectively. Preferably, each gripperis designed to grip the entire range of dimensions for the respectivecable component. For example, the third gripper 44′ is preferablydesigned to hold the cable jacket of fiber optic cables having adiameter of 0.9 mm to 3.5 mm, while the first gripper is preferablydesigned to hold bare fibers ranging from 35 microns to 250 microns indiameter.

With reference to FIGS. 3 and 4, each gripper 44 of one advantageousembodiment preferably has a pair of opposed gripper arms 44 a, 44 b forengaging the respective cable component, such as the outer jacket of thefiber optic cable, the buffered optical fiber or the bare optical fiber.In order to securely engage the respective cable component, the firstgripper arm can include a recessed or V-shaped section, while the secondgripper arm can include a corresponding V-shaped protruding section.Each gripper can also include a respective actuator 46 for opening andclosing the pair of opposed gripper arms. In order to further controlthe movement of the gripper arms, each gripper can include one or morerails 48 along which the gripper arms move. Although the grippers areshown to include actuators, the grippers can include a variety of othermeans for biasing the pair of opposed gripper arms into contact with therespective cable component. For example, the grippers can include one ormore springs for biasing the protruding section of the second gripperarm into the recessed section of the first gripper arm so as to securelyhold the respective cable component therebetween.

In one advantageous embodiment, the third gripper 44′ designed to engagethe cable jacket is mounted upon an adjustable platform 49 that issupported above the platform 36 of the optical fiber cartridge 34 bymeans of a second set of rails 53. As shown in FIGS. 3A and 3B, thethird gripper also preferably includes a second actuator 50 for movingthe adjustable platform relative to the platform of the optical fibercartridge. By opening the first and second grippers designed to hold thebare optical fiber and the buffered optical fiber while concurrentlyengaging the cable jacket with the third gripper, the fiber optic cablecan be moved relative to the platform of the optical fiber cartridge byadvancing or retracting the second actuator. As such, the end portion ofthe fiber optic cable can be extending beyond the optical fibercartridge, if so desired. The actuators associated with the first,second and third grippers are preferably controlled by the centralcontroller 30 so as to precisely position the fiber with respect to thecable for a variety of cable and fiber diameter combinations.

In order to begin the cable and fiber preparation process referenced byblock 200 of FIG. 6A, fiber optic cable is first wound upon the opticalfiber cartridge 34. Initially, the controller 30 actuates a cable feeder51 to feed a firs end of the fiber optic cable from the rear of thecartridge through the first, second and third grippers 44 of the firstgripping means as shown in FIG. 5A. In the embodiment of FIG. 3A inwhich the platform includes a sidewall 52, the first end of the fiberoptic cable is also extended out through an opening 54 defined in thesidewall. The first, second and third grippers of the first grippingmeans then securely grip the first end of the fiber optic cable.

The optical fiber cartridge assembly 34 also includes means, such as anexternally engaged rotating driver motor, for rotating the platform 36,in response to a command from the controller 30, so as to wind thepredetermined length of fiber optic cable about the reel. As shown inthe embodiment of FIG. 3A, the platform can include tapered sidewalls 52that increase in height from the rear of the cartridge toward the frontof the cartridge to guide the fiber optic cable over the grippers 44while the fiber optic cable is being wound upon the reel. However, theplatform need not include sidewalls. Instead, the optical fibercartridge assembly can include means, such as an axle 56 having atelescoping shaft, for raising the reel relative to the platform asshown in FIG. 3B during the rotation to the platform such that the fiberoptic cable passes over the grippers while being wound upon the reel.Once the predetermined length of fiber optic cable is wound upon thereel of this embodiment, the reel is lowered onto the platform andsecured at a fixed position.

Typically, the controller 30 initiates rotation of the platform 36 whichcontinues until the predetermined length of fiber optic cable is woundupon the reel. Thereafter, the rotating means, under control of thecontroller, halts rotation of the optical fiber cartridge with theoptical fiber cartridge facing in the opposite direction so as toposition the fiber optic cable over the first, second and third grippers44 of the second gripping as shown in FIG. 5B.

The cable cutting and marking unit 32 of the automatic fiber opticconnectorization apparatus 20 includes a cutter 58 responsive tocommands from the controller. The cutter is designed to cut the cablenear the forward edge of the optical fiber cartridge 34 once thepredetermined length of fiber optic cable is wound upon the reel 38 toform a second end that extends loosely from the reel. The controller 30then rotates the reel relative to the optical fiber cartridge to retractthe second end of the fiber optic cable toward the rear of the opticalfiber cartridge until the second end of the fiber optic cable isrearward of the third gripper 44′ of the second gripping means. Thecontroller then reverses the direction of rotation of the reel such thatthe second end of the fiber optic cable is pushed through the first,second and third grippers of the second gripping means so as to extendto the forward edge of the optical fiber cartridge. In the embodiment ofFIG. 3A in which the platform includes a sidewall 52, the first end ofthe fiber optic cable is also extended out through another opening 60defined in the sidewall. The first, second and third grippers of thesecond gripping means then engage the second end of the cable. Theoptical fiber cartridge loaded worth the predetermined length of fiberoptic cable and having both end portions held by respective grippers maythen be transported by robotic arm or other means throughout the variousunits of the automatic fiber optic connectorization apparatus forprocessing.

Once the fiber optic cable has been wound upon the reel 38 and has beencut on the specified length as shown in block 201 of FIG. 6B, the cablecutting and marking unit 32 of the automatic fiber opticconnectorization apparatus 20 marks the fiber optic cable. See block202. For example, the cable cutting and marking unit can mark the fiberoptic cable with a part number provided by the system operator or thefiber optic cable and connector database 26. In addition, the cablecutting and marking unit can affix. installation and/or terminationinformation labels to one or both ends of the fiber optic cable tofacilitate subsequent installation of the fiber optic cable.

The automatic fiber optic connectorization apparatus 20 also includes acable stripping unit 62 for stripping the end portion of the fiber opticcable such that the strength members, the coating buffer and the opticalfiber extend beyond the outer jacket by respective predetermined striplengths. See also blocks 203-206 of FIG. 6B. As known to those skilledin the art, the predetermined strip lengths by which the strengthmembers, the coating buffer and the optical fiber extend beyond theouter jacket are determined based upon the type of connector to bemounted upon the end portion of the fiber optic cable and theconnectorization procedure. Typically, the central computer 22 accessesthe fiber optic cable and connector database 26 to determine thediameter and correct strap length for each cable component once the typeof fiber optic cable and the type of connector to be mounted upon theend portion of the fiber optic cable has been input. As such, theautomatic fiber optic connectorization apparatus of the presentinvention allows a unique advancement by polishing the fiber to acritical length suitable for each connector type and then preciselysecuring the fiber within the connector ferrule for the desiredcombination of connector and fiber endface geometry.

The automatic fiber optic connectorization apparatus 20 is designed tomount a variety of types of connectors upon a variety of types of fiberoptic cables. For mounting a connector upon a particular type of fiberoptic cable, the central computer 22 must generally obtain therespective diameter of each cable component from the fiber optic cableand connector database 26 since different types of fiber optic cableshave cable components with different diameters. Referring now to FIG. 7,for example, a single mode fiber optic cable 64 is illustrated which hasan optical fiber 66 having a core that is approximately 6 microns indiameter and a cladding layer that is approximately 125 microns indiameter. As shown, the fiber core and cladding are oftentimes encasedin a coating or polyamide buffer 70 having a diameter of approximately174 microns that is, in turn, surrounded by a cable jacket 72, typicallyformed of a flouropolymer, polyvinylchloride (PVC) or polyurethane. Itshould be apparent that the foregoing dimensions are provided forpurposes of example and not limitation since there are a number of otherstandard sizes of fiber optic cables, such as fiber optic cable having acore diameter of approximately 100 microns and a cladding diameter of140 microns and fiber optic cables can include a core diameter of 400microns and a cladding diameter of 480 microns. Although not shown, manyfiber optic cables include strength members, typically formed offiberglass or KEVLAR, that extend between the cable jacket and thebuffer. in addition, although a fiber optic cable of tight tubeconstruction is illustrated, the method and apparatus of the presentinvention could also be utilized in conjunction with fiber optic cableshaving a loose tube construction.

In order to strip the desired amount of each of the cable componentsfrom the end portion of the fiber optic cable, the fiber optic cable ispositioned such that the end portion extends beyond the respectivegrippers 44. In this regard, the controller 30 commands the first andsecond gripping means to temporarily release the fiber optic cable andthe reel 38 is rotated so as to extend one end portion of the fiberoptic cable beyond the respective grippers by a preferred amount. Thegrippers then re-engage and hold the fiber optic cable in place duringthe stripping process. In order to strip the other end portion of thefiber optic cable, the grippers are again opened and the reel is rotatedin the opposite direction such that the other end portion of the fiberoptic cable extends beyond the respective grippers by a sufficientamount prior to again closing the grippers.

As shown in FIG. 2 and in more detail in FIG. 7, the automatic fiberoptic connectorization apparatus 20 also includes a fiber cleaving unit74, including a scribe, for cleaving the end portions of the fiber opticcable in order to provide a suitable end face. See block 206 of FIG. 6B.In order to properly cleave the end portion of the fiber optic cablesuch that the end face is perpendicular to the longitudinal axis of thefiber optic cable, the fiber optic cable must be precisely positionedrelative to the scribe. Thus, the automatic fiber optic connectorizationapparatus preferably includes a work table having one or moreregistration pins 78. In addition, the automatic fiber opticconnectorization apparatus preferably includes one or moremicropositioners that operate in response to commands by the controller30 for precisely positioning the optical fiber cartridge 34 relative tothe registration pins. As shown in FIGS. 3A and 3B, the automatic fiberoptic connectorization apparatus can also include a solenoid 80 formaintaining the optical fiber cartridge in a fixed position against theregistration pins on the work table once the optical fiber cartridge hasbeen properly positioned by the micropositioner. Due to the design ofthe optical fiber cartridge, the grippers 44 maintain the fiber opticcable parallel to the surface of the work table, thereby permitting thecleaved end face to be perpendicular to the longitudinal axis of thefiber optic cable. In addition, the fiber cleaving unit preferablyincludes horizontal and vertical actuators for controllably positioningthe scribe relative to the fiber optic cable.

After cleaving each end face of the optical fiber of the fiber opticcable, the end faces are ground and polished to remove any defects andto provide the desired shape as shown generally in block 300 of FIG. 6Aand in more detail in blocks 301-304 of FIG. 6D. According to oneembodiment of the present invention, the automated fiber opticconnectorization apparatus 20 includes an end face polishing unit 81that includes a cassette 82 for preparing the end face of an opticalfiber, such as by grinding, polishing or otherwise cleaning the end faceof the optical fiber. As shown in FIGS. 8A and 8B, the cassette includesa housing 84 defining a window 86. The cassette also includes a supplyreel 88 and a take up reel 90 disposed within the housing and apreparatory tape 92 extending between the supply reel and the take upreel. For example, the preparatory tape may be a polishing or lappingstrip that includes an abrasive material. Typically, the preparatorytape also includes a cleaning strip that includes a cleaning solution.

The cassette 82 of this embodiment also includes means for directing thetare 92 by the window 86 defined by the housing 84 such that the tapewill contact the end face 94 of the optical fiber 95. While thedirecting means can include any type of guides known to those skilled inthe art, the directing means of one advantageous embodiment includes apair of guides 96 positioned on opposite sides of the window fordirecting the preparatory tape in a direction parallel to the frontsurface 84 a of the housing that defines the window. The directing meansof one advantageous embodiment also includes a resilient pad 98,typically formed of a rubber or plastic material, that is aligned withthe window and is disposed interior of the preparatory tape within hehousing. As such, the resilient pad supports the preparatory tape byproviding a backing surface during contact with the end face of thefiber optic cable. In order to protect the preparatory tape and maintainprocess control as the tape advances from the supply reel 88 to the takeup reel 90, the cassette also preferably includes a pair of planarguides 100 inset within the front surface of the housing on either sideof the window and formed of a material, such as a flouropolymer, havinga relatively low coefficient of friction to avoid abrading the tape uponthe inside surface of the cassette which could introduce contaminates tothe tape and, in turn, to the end face of the fiber optic cable.

The cassette 82 also includes means for advancing the tape following usesuch that a fresh portion of the tape 92 is presented with the windowfor grinding, polishing, cleaning or otherwise preparing the end portionof the next optical fiber. While the tape could be advanced in a varietyof manners, the supply reel and/or the take up reel of one embodiment ofthe cassette may include an axle 102 that extends outward beyond thehousing 84. As such, the axle can be rotated following use of the tapeto provide incremental advancement of the tape.

The end face polishing unit 81 also includes means for controllablymoving the cassette 82 relative to the end face 94 of the optical fiber95 in response to commands by the controller 30 to thereby polish theend face of the optical fiber. In one advantageous embodiment shown inFIG. 8A, the end face polishing unit includes one and, more preferably,a pair of actuators 104, such as piezoelectric actuators, mounted onrespective sides of the cassette. In order to provide movement of thecassette parallel to the end face of the optical fiber in two mutuallyperpendicular directions, the pair of actuators should be placedadjacent sides of the cassette that are also perpendicular in responseto predetermined signal patterns provided to he actuators by thecontroller, the actuators will move the cassette and, more particularly,the tape 92 in a circular, figure eight or other pastern as required bythe type of optical fiber being polished and the type of connector to bemounted upon the optical fiber. Typically, information defining thepredetermined signal patterns that will be provided by the controller todrive the actuators can also be provided by the fiber optic cable andconnector database 26.

In addition, the cassette 82 could be positioned, typically by means ofmicropositioners that respond to commands from the controller 30, tochange its direction of contact with the end face 94 of the opticalfiber. For example, a cassette that is otherwise oriented such that thetape is in a direction perpendicular to the Longitudinal axis of theoptical fiber can be tilted either upwards or downwards and/or to theright or to the left to present a different angle of attack, therebypermitting further control in shaping the resulting end face of theoptical fiber.

As described below, the same or a similar cassette 82 to that shown inFIGS. 8A and 8B and described above may be used for applying cleaningsolution and for removing dirt and debris as well as excess adhesive orepoxy from the end face 94 of the optical fiber 95. In this embodiment,the preparatory tape 92 can include cleaning pads that are provided inthe form of an elongated strip that advances between the supply and takeup reels.

As shown in FIG. 1, the automatic fiber optic connectorization apparatus20 defines an enclosed space within which the optical fiber is cleaved,ground and polished. The cleaving, grinding and polishing of an opticalfiber creates dust and debris which may be classified as hazardouswaste. As such, the automatic fiber optic connectorization apparatuspreferably includes a positive pressurization and ventilation system,i.e., a vacuum system, for capturing and removing the fiber dust anddebris as set forth in blocks 302 and 304 of FIG. 6D.

Typically, the automatic fiber optic connectorization apparatus 20performs multiple cleaning and polishing steps. For example, the endface of the optical fiber is typically ground, and is then cleaned toremove dust, dirt and grinding compounds and is finally subjected to oneor more polishing steps in which the end face of the optical fiber ispolished with increasingly finer abrasives in each successive polishingstep. The multiple cleaning and polishing steps can be provided byrepeatably changing the preparatory tape 92 within the cassette 82 or bymoving the optical fiber from station to station, each of which includesa different cassette for grinding, cleaning or polishing the end face ofthe optical fiber.

After grinding and polishing the end face of the optical fiber, the endface is inspected as shown in block 400 of FIG. 6A. If the end face isnot acceptable, the end face is repolished or otherwise reworked, ispossible, prior to being re-inspected. If the end face cannot besatisfactorily repolished or otherwise reworked, the fiber optic cablewill be rejected. Once rejected, the fiber optic cable may be re-cleavedand completely reprocessed. Alternatively, the rejected fiber opticcable may be discarded.

As shown in FIG. 2, the automatic fiber optic connectorization apparatus20 includes an end face inspection unit 106 (also referred to as anautomated optical fiber inspection apparatus) for capturinginterferrograms of the end face of the optical fiber that will beutilized to characterize the geometry of the end face. See block 401 ofFIG. 6E. As described below, typical interferrograms of an end face ofan optical fiber are shown in FIGS. 9A-9D.

The end face inspection unit 106 includes or is associated with animaging system 108 for obtaining an image of the end face of the opticalfiber. Preferably, the imaging system obtains and digitizesinterferrograms of the end face of the optical fiber and then stores thedigitized interferrograms in a memory device. See block 402.

According to one advantageous embodiment shown in FIG. 14, the imagingsystem 108 includes a scanning camera 110, an interferometer 111 and anassociated micropositioner 112 for moving the camera in increments, suchas 6 micron increments, in order to scan the surface of the end face 94of the optical fiber 95 at different phase shift positions per exposure,such as π/2 phase shift positions per exposure. Thus, the imaging systemof this embodiment can generate interferrograms at each of a number ofdifferent phase shifts, such as a hundred or more different phaseshifts. For example, FIGS. 9A-9D depict the interferrograms generated atfour different phase shifts, namely, π/2, π, 3π/2 and 2π. For example,one embodiment of the imaging system which scans at 6 micron incrementsand can take up to 700 images at a time is commercially available and isdesignated as a Physic Instrument (PI) from Nordland Products, Inc.However, the imaging system can include other frame grabber software, ifso desired.

The intensity measurements for the pixel located at (x,y) in each of thefour interferrograms (I₁, I₂, I₃ and I₄) obtained by the imaging systemare:

I₁(x,y), I₂(x,y) I₃(x,y), I₄(x, y)

In addition to displaying the interferrograms upon a video display 114,the imaging system 108, such as the Physic Instrument from NordlandProducts, Inc. or other phase shift analysis software, generates acomposite image which is then grey scale normalized to a single phasepattern as shown schematically in FIGS. 9E and 10. See blocks 403-404 ofFIG. 6E.

In order to determine a composite image COMP(x,y) based upon the fourinterferrograms, the value representing phase modulo π/2 for each pixelof the composite image can be calculated by one method as follows:$\Phi = \frac{{{I_{4}\left( {x,y} \right)} - {I_{2}\left( {x,y} \right)}}}{{{I_{1}\left( {x,y} \right)} - {I_{3}\left( {x,y} \right)}}}$

Since the above function only generates an angular value in the firstquadrant, each pixel of a composite image having an accurate angle witha value in the range of 0 to 2π radian, i.e., the phase module 2π, isdetermined by the following table (in which “Phase” represents the valueof the respective pixel of the composite image) with the actual signs,i.e., prior to taking the absolute value, of the numerator and thedenominator of taken into consideration as follows:

TABLE I Numerator Denominator Phase (radian) + + Φ + − π − + ∘ π/2 − +2π − − − π + Φ − ∘ 3π/2 ∘ − π ∘ + ∘

FIG. 10 shows the above method applied to calculate the composite imageat a pixel located at (x,y), i.e., COMP(x,y), based upon the intensityvalues of pixels from four interferrograms I₁, I₂, I₃, and I₄ at thesame location (x,y). As also shown in FIG. 10, the composite image istypically normalized by converting the phase of each pixel of thecomposite image (0 to 2π) to a corresponding grey scale value (0 to 255,i.e., 0 to 2⁸, if there are 8 bits per pixel). In addition, the imagingsystem subjects the composite image to a rotation invariancetransformation to convert the positional relationship information of thedata set from polar to rectangular for lateral movement of the imagerather than rotational movement, for pattern comparison processing ofthe composite image as known to those skilled in the art. See block 405of FIG. 6E. As shown in FIG. 11, the composite image can also be edgeenhanced prior to the normalization process. For example, the compositeimage shown in FIG. 11A can be edge enhanced to generate the image shownin FIG. 11B. As known to those skilled in the art, the subsequentanalysis of the image, typically by means of fuzzy logic, is facilitatedby edge enhancing the composite image.

For purposes of illustration, FIGS. 12A and 13A depict composite imagesof the end faces of two different optical fibers. As FIGS. 12 and 13indicate, the composite images provide, among other things, Informationrelating to polishing depth and fiber face contour. For example, FIGS.12B-12D illustrate various contour maps derived from the composite imageof FIG. 12A. In particular, FIG. 12B is a three dimensional mesh view ofthe composite image, FIG. 12C is a display of the spherical fittingerror and FIG. 12D is a surface contour display. As shown, the end faceof the optical fiber illustrated in FIGS. 12A-12D is unacceptable due tothe peak on one side of the end face that should be correctable bypolishing. Likewise, FIGS. 13B-13D illustrate the various contour mapsof the composite image of FIG. 13A. In contrast to the correctable endface of FIGS. 12A-12D, the end face of FIGS. 13A-13D is not onlyunacceptable, but is also uncorrectable since one side of the end faceis deeply pitted, if not fractured.

The end face inspection unit 106 also includes means for comparing theimage, i.e., the composite image or, more preferably, the normalizedimage, of the end face of the optical fiber with predefined datarelating tabto at least one characteristic of the end face of theoptical fiber to automatically determine if the optical fiber isacceptable. This comparison can be performed in several differentmanners without departing from the spirit and scope of the presentinvention. As shown in FIGS. 14 and 15, for example, the composite imagecan be compared to several reference images that have been previouslyclassified as either acceptable or unacceptable. By determining which ofthe reference images is most similar to the composite image, i.e., thebest match, the end face inspection unit and, more particularly, thecomparing means also classifies the composite image as acceptable orunacceptable. See blocks 407-409 of FIG. 6E. By directly inspecting theend face geometry by means of pattern comparison, instead of featureextraction, and by determining the best match instead of an exact match,the comparing means of the present invention greatly simplifies andaccelerates the overall inspection process.

The reference images are typically downloaded to a memory deviceassociated with the end face inspection unit 106. For example, thereference images can be downloaded from an external database 26, such asthe fiber optic and connector database. Alternatively, the end facefinishing inspection unit can include a video camera 116 and a videorecorder 118 for recording the reference images of acceptable andunacceptable end faces for subsequent downloading to a memory device forcomparison with the composite image, as shown in FIG. 14. As a result,the inspection criteria can be changed by merely changing the referenceimages without any alterations to the software which could be quitecomplex. In addition, the automatic finer optic inspection system caninclude artificial intelligence which supplements the reference imagesto include actual images of the end faces of some or all of the opticfibers that have undergone inspection and been classified as eitheracceptable or unacceptable.

The end face inspection unit 106 can also include a fuzzy logic workstation 120 for comparing the composite image with the various referenceimages to determine if the surface configuration of the end face of theoptical fiber is acceptable. Typically, the composite image is notcompared directly to the reference images. Instead, as shown in FIG. 15,the comparing means generally compares a two dimensional fast fouriertransform of the composite image to the two dimensional fast fouriertransforms of the reference images. Typically, the two dimensional fastfourier transforms of the reference images are also stored in the memorydevice of the imaging system 108. In one embodiment, the fuzzy logicwork station includes a NeuralLogix ASD110 Fuzzy Pattern Comparatorwhich compares the various reference images to the composite image todetermine the best match. As shown in FIG. 14, both the imaging systemand the fuzzy logic work station can have a monitor 122 and a keyboard124. In addition, the fuzzy logic work station can have a printer 126.Although illustrated to be separate from the central computer 22, thefuzzy logic work station can be incorporated within the computer, if sodesired.

During the construction of the composite image, the imaging system, suchas the Physic Instrument (PI) by Nordland Products, Inc., alsopreferably extracts a number of features relating to the fiber end-facegeometry. See block 406 of FIG. 6E. Although the extracted features arenot typically utilized during the process of determining if the fiberend-face is acceptable as shown in FIG. 18, the extracted features arepreferably stored along with other data relating to the particularoptical fiber for subsequent review and/or analysis. In one advantageousembodiment, the features extracted from the composite image include: (1)radius of curvature of the end face, (2) spherical-fitting error, (3)fiber height (protruding or recessed), (4) fiber core diameter, (5)fiber cladding diameter, (6) concentricity of the end face, and (7)fringes within the Region of Interest (ROI) including, at least, thefiber end-face.

As shown in Table I, the normalized composite image of theinterferrogram is typically stored in the memory of the imaging system108 along with an identification number, a two dimensional surfaceprofile, the fourier coefficients of the two dimensional surfaceprofile, the various features extracted from the composite image and anindication as to whether the end face of the optical fiber is acceptableor unacceptable, i.e., pass or fail. As such, the automated fiber opticconnectorization apparatus maintains detailed records relating to theconnectorization and inspection of each fiber optic cable.

TABLE II Field Field Name Data Type 1 Record I.D. Text/Numeric 2Interferrogram (Image) OLE Object 3 2D surface profile Binary/Bitmap 4Fourier Coefficients (2D Numeric Image) 5 Radius of Curvature of theNumeric End Face 6 Spherical fitting Error Numeric 7 Fiber HeightNumeric 8 Fiber, Core Diameter Numeric 9 Fiber Cladding Diameter Numeric10 Surface Slope Numeric 11 Diameter of Region of Numeric Interest 12Pass/Fail Classification Yes/No

In addition to merely determining whether the end face of an opticalfiber is acceptable or unacceptable, the end face inspection unit 106also preferably determines if an unacceptable end face can be corrected,such as by further polishing the end face, or if the optical fiber mustbe totally reworked or discarded. See block 410 of FIG. 6E. For purposesof illustration, FIGS. 16 and 17 depict the end faces or a number ofoptical fibers that include defects that are correctable anduncorrectable, respectively. It should be apparent that data, i.e.,reference images, representative of the various end faces of the opticalfibers of FIGS. 16 and 17 would be compared to the composite image of anunacceptable end face to determine if the defect is correctable.

In particular, FIGS. 16A-16C shows several end faces having defectswhich fail inspection, but can be repaired by repolishing. These defectsinclude an upwardly protruding lip, scratches and hackle. Each of thesedefects can be corrected by the removal of material from the end face,such as with further polishing. In contrast, FIG. 17 shows several endfaces having defects which cannot be corrected. These defects include ascore/indent, a rolloff on one side, a chip out of the side, cracks, ashattered end face and an angled end face. These defects are notcorrectable and would require recleaving and complete reprocessing.

The automatic fiber optic connectorization apparatus 20 also includesmeans for obtaining the components that will be mounted upon the endportion of the fiber optic cable once the end face of the optical fiberis found to be acceptable. In particular, the automatic fiber opticconnectorization apparatus obtains both the connector parts and thesupplies, such as the epoxy, required to mount the specified type ofconnector upon the end portion of the fiber optic cable. As describedabove, the system operator generally provides an indication of the typeof connector to be mounted upon the fiber optic cable and the fiberoptic cable and connector database 26 defines the various parts andsupplies required to assemble and mount the specified type of connector.According to one embodiment, the automatic fiber optic connectorizationapparatus includes a plurality of mechanical grippers or other types ofrobotic arms that operate under control of the controller 30 forautomatically obtaining the various parts and supplies that have beenpreviously cleaned and sorted into different predetermined bins asshown. Typically, the parts are cleaned by ultrasonic and spray methodsand are then inspected to insure that the parts are sufficiently clean.Thereafter, the mechanical grippers obtain the necessary parts fromdifferent predetermined bins into which the parts have been sorted orfrom sequential feed reels as known to those skilled in the art.

The automatic fiber optic connectorization apparatus 20 also includesmeans, typically including a connector bonding unit 128, for assemblingthe components upon the end portion of the fiber optic cable once thenecessary parts and supplies have been obtained. In particular, theconnector bonding unit generally bonds the ferrule to the end portion ofthe optical fiber with an epoxy. See block 500 of FIG. 6A. As known tothose skilled in the art, the epoxy can be two-part resin and catalystor a B-stage epoxy depending upon the type of connector to be mountedupon the fiber optic cable. As described above, the type of epoxy andthe placement of the epoxy relative to he optical fiber and ferrule istypically defined by the fiber optic cable and connector database 26.

If a two-part epoxy is utilized to bond the ferrule to the opticalfiber, the connector bonding unit 128 initially inserts the epoxy intothe ferrule and the ferrule is then positioned on the optical fiber suchthat the end portion of the optical fiber extends through the bore ofthe ferrule. See blocks 501-502 of FIG. 6F. Preferably, the opticalfiber extends through the bore of the ferrule such that the end face ofthe optical fiber is aligned with the end of the ferrule as required tomeet the input performance requirements and connector assemblyparameters provided by the system operator, the wire data list or othersource. If the optical fiber is to extend beyond the end of the ferrule,the ferrule is then retracted such that the end portion of the opticalfiber extends beyond the end of the ferrule by the desired amount. If aB-stage epoxy is instead utilized to bond the ferrule to the end portionof the optical fiber, the connector bonding unit fully inserts theoptical fiber into the ferrule such that the optical fiber need notlater be repositioned.

As shown in blocks 503-504 of FIG. 6F, the epoxy is then cured, excessepoxy is removed from the end face of the optical fiber, and she cableassembly is inspected. Since most epoxy must be heat cured, theconnector bonding unit typically includes a heater 130 for curing theepoxy. To cure epoxy having a relatively small cure time, such as aB-stage epoxy, the end portion of the optical fiber is held in place andthe heaters positioned near the end portion of the optical fiber for therequired cure time. Alternatively, for epoxy having a relative long curetime, such as two-part liquid epoxy resins, the connector bonding unitmay include a separate curing station to simultaneously heat a number offiber/ferrule combinations. The connector bonding unit preferablycontrols the temperature of the heater and the cure time in accordancewith the data provided by the fiber optic cable and connector database26. For example, B stage preformed epoxy is generally cured at 150° C.for 1 hour. Alternatively, two part epoxy is typically cured by rampingthe heat up to 80° C. for 1 hour, followed by a heat soak at 120° C. forone hour, and a post-cure heat soak at 150° C. for one hour. As known tothose skilled in the art, however, some epoxies require different cureschedules depending on the cable/connector utilization.

Once the epoxy has been cured, the connector bonding unit 128 removesexcess epoxy from the end face of the optical fiber, the end of theferrule and other undesirable locations. As described above, theconnector bonding unit can utilize a cassette 82 as shown in FIGS. 8Aand 8B that includes a cleaning strip for cleaning the connectorizedoptical fiber. In one advantageous embodiment, the cleaning strip isimpregnated with a clearing solution for application to the end face ofthe optical fiber. After the cleaning solution has been applied, wipedand dried, the end face of the optical fiber can be inspected onceagain, such as by means of the imaging system 108 described above or theoptical performance inspection unit 132 described below and shown anblock 600 of FIG. 6A.

If the end face of the optical fiber is to be concave, the automaticfiber optic connectorization apparatus 20 preferably further polishesthe end face of the optical fiber after the ferrule has been mountedthereon, but prior to cleanings the end face of the optical fiber. Sincethe ferrule is harder than the optical fiber, the abrasive carried bythe polishing strip will preferentially remove material from the endface of the optical fiber, thereby forming a concave surface.

The automatic fiber optic connectorization apparatus 20 and, moreparticularly, the controller 30 also obtains and mounts any additionalconnector parts or hardware that are required pursuant to the fiberoptic cable and connector database 26. See block 601 of FIG. 6G. For a16 gauge connector, for example, the automatic fiber opticconnectorization apparatus would also mount a spring, an outer sleeveand a guide sleeve. For an NTT FC connector, the automatic fiber opticconnectorization apparatus would also mount a barrel, a strain reliefboot, a coupling nut and a strength member retainer.

Once the additional connector parts have been assembled, the end face ofthe optical fiber and the connector mounted thereto are preferablycleaned and a performance inspection is conducted. In order to conductthe performance inspection, the automatic fiber optic connectorizationapparatus 20 and, more particularly, the optical performance inspectionunit 132 aligns the opposed ends of the fiber optic cable 148 withrespective ends of a pair of reference optical fibers extending from atest station 150 and performs an optical loss measurement, typicallyunder control of the central computer 22 and/or the controller 30. Seeblock 602 of FIG. 6G. As shown in FIG. 19, the test station typicallyincludes an optical source 152 for providing predetermined optical inputto an input optical fiber. In addition to launching the predeterminedoptical input into a first end of the connectorized fiber optic cableunder test as set forth by block 603, the test station also preferablyincludes a coupler or optical splitter 154 for coupling the inputoptical fiber to a medial portion of a second optical fiber having ananti-reflection block 156, such as an index matching gel, at one end,and a first detector or power meter 158 at the other end. Thus, theconfiguration of the test station shown in FIG. 19 forms a fiber opticinterferometer to permit back reflections from the fiber optic cableunder test to be measured by the first detector or power meter. The teststation also preferably includes a second detector or power meter 160optically connected to the second end of the connectorized fiber opticcable under test. See block 604. Based upon the readings of the firstand second detectors, the optical performance inspection unit candetermine the back reflection and optical loss of the fiber opticcable/connector assembly as shown in block 605. For most optical fibers,the optical loss should be less than 1 dB. The optical performance ofthe optical fiber, including the back reflections and optical loss, ispreferably stored in memory for later display and hard copy print,thereby further improving the recordkeeping associated with theconnectorization and inspection process.

Preferably, the optical performance inspection unit includes one or moremicropositioners for automatically aligning the opposed ends of theconnectorized fiber optic cable to respective ends of the optical fibersof the test station with the same tolerances as required during themating of a pair of connectors. In this regard, the launch conditionswill preferably be 100/100, i.e., 100% of the numerical aperture of theoptical fiber under test and 100% of the core diameter of the opticalfiber under test. In order to insure that the test station is properlycalibrated, the test station preferably periodically measures theoptical loss across a reference cable with a known loss.

Although not heretofore described, the product conformity inspectionunit 138 preferably checks the components, i.e., the fiber optic cableand the connector components, prior to the connectorization process toinsure that the components meet predefined standards or are withinacceptable tolerances. See, for example, blocks 251-255 of FIG. 6C.Typically, the predefined tolerances and acceptable tolerances areprovided by the fiber optic cable and connector database 26 for avariety of features, such as fiber concentricity, the outer diameter ofthe fiber cladding, the diameter of the fiber core, the inside andoutside diameter of the connector ferrule and the ferrule concentricity.The product conformity inspection unit generally includes a visionsystem, including a camera and associated frame grabber software, forobtaining an image of the various components for subsequent analysis bythe central computer 22 and associated software. In addition toreporting those components which fail to meet specifications as shown inblock 255, the measured features of the various components are alsopreferably stored, thereby generating a statistical database. Bydetermining the physical parameters of the various components of theconnectorized fiber optic cables which ultimately have the best opticalperformance, the automated fiber optic connectorization and inspectionapparatus 20 can also learn to select those components which have thephysical parameters which are generally associated with fiber opticcables that perform acceptably.

By providing for the automatic connectorization of optical fibers, theautomatic fiber optic connectorization method and apparatus 20 of thepresent invention significantly reduces the time and labor required tomount connectors upon the end portions of fiber optic cables, therebyIncreasing production capacity. As a result, the automated fiber opticconnectorization apparatus can be readily operated by technicians withvery little training. The efficiency and yield of the automaticconnectorization process or the present invention is further advanced bythe automated optical fiber inspection apparatus of one embodiment thatinsures that the optical fibers nave been properly polished prior tomounting of the connectors and, if an optical fiber is unacceptable,automatically determines if the optical fiber must be repolished orotherwise reworked. In contrast to conventional automatedconnectorization techniques, the automated fiber optic connectorizationapparatus of the present invention can advantageously mount any one of aplurality of types of connectors upon the end portion of a fiber opticcable based upon input by the system operator or other source, therebypermitting rapid customization of the automated fiber opticconnectorization apparatus.

Many modifications and other embodiments of the invention will come tomind to one skilled in the art to which this invention pertains havingthe benefit of the teachings presented in the foregoing descriptions andthe associated drawings. Therefore, it is to be understood that theinvention is not to be limited to the specific embodiments disclosed andthat modifications and other embodiments are intended to be includedwith the scope of the appended claims. Although specific terms areemployed herein, they are used in a generic and descriptive sense onlyand not for purposes of limitation.

That which is claimed is:
 1. An automated optical fiber inspectionapparatus for inspecting an end face of an optical fiber, the automatedoptical fiber inspection apparatus comprising: a memory device forstoring images of acceptable end faces and unacceptable end faces; animaging system for obtaining an image of the end face of the opticalfiber; and means, responsive to said imaging system, for comparing theimage of the end face of the optical fiber with the images of acceptableend faces and unacceptable end faces to automatically determine if theoptical fiber is acceptable.
 2. A automated optical fiber inspectionapparatus according to claim 1 further comprising a test station fordetermining the optical performance of optical fiber.
 3. An automatedoptical fiber inspection apparatus comprising: a memory device forstoring images of acceptable end faces and unacceptable end faces; animaging system for obtaining an image of the end face of the opticalfiber; and means, responsive to said imaging system, for comparing theimage of the end face of the optical fiber with the images of acceptableend faces and unacceptable end faces to automatically determine if theoptical fiber is acceptable; and means, responsive to said comparingmeans, for automatically determining if the end face of an unacceptableoptical fiber can be corrected.
 4. A method for automatically inspectingan end face of an optical fiber, the method comprising the steps of:providing a memory device for storing images of acceptable end faces andunacceptable end faces; obtaining an image of the end face of theoptical fiber; and comparing the image of the end face of the opticalfiber with the images of acceptable end faces and unacceptable end facesto automatically determine if the optical fiber is acceptable.
 5. Amethod according to claim 4 further comprising the step of testing theoptical fiber to determine the optical performance of the optical fiber.6. A method for automatically inspecting an end face of an opticalfiber, the method comprising the steps of: providing a memory device forstoring images of acceptable end faces and unacceptable end faces;obtaining an image of the end face of the optical fiber; comparing theimage of the end face of the optical fiber with the images of acceptableend faces and unacceptable end faces to automatically determine if theoptical fiber is acceptable; and automatically determining if the endface of an unacceptable optical fiber can be corrected.